Positron emission tomography imaging system, detector, data processing apparatus, computer readable program product having positron emission tomography imaging program for user terminal, and method for positron emission tomography diagnosis

ABSTRACT

A positron emission tomography imaging system includes a detector configured to detect radiation emitted from an object to be examined, a data processing apparatus configured to reconstruct image data for positron emission tomography diagnosis from detection data obtained from the detector, and a user terminal configured to obtain desired information by operating the detector and the data processing apparatus. The detector includes a detection part having a plurality of detection elements configured to detect the radiation emitted from the object to be examined for every designated timing, and an event information file generation part configured to generate an event information file based on the detection data obtained from the detector.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to positron emission tomography imaging systems, detectors, data processing apparatuses, computer readable program products having positron emission tomography imaging programs for user terminals, and methods for positron emission tomography diagnosis, and more particularly, to a positron emission tomography imaging system, detector, data processing apparatus, computer readable program product having positron emission tomography imaging program for a user terminal, and method for positron emission tomography diagnosis, whereby cost for equipment at a user side can be reduced and tolerance against an obstruction can be improved by load-sharing.

2. Description of the Related Art

A positron emission tomography (hereinafter “PET”) apparatus has been used for imaging the internal distribution of a radioactive isotope (hereinafter “RI”) given into an object to be examined. In a diagnostic method in which the PET apparatus is used, first a positron emitting radioactive compound is introduced into the body of the object to be examined by an injection, inhalation, or the like. The radioactive compound introduced in the body of the object to be examined is metabolized and accumulated in a specific portion of the body. At this time, the positron is emitted from the RI tagged for the radioactive compound. The emitted positron and a vicinage electron are annihilated and two gamma ray photons are emitted in opposite directions. An image is reconstructed by computer-processing from information about the detected photons, reconstructed image data in the object to be examined can be obtained. The object to be examined can be diagnosed by the reconstructed image data.

There is a scintillation detector, a semiconductor detector, or the like, as a means for detecting a detect signal in a conventional PET apparatus. Particularly, the semiconductor detector directly detects the gamma ray while the scintillation detector requires two conversion steps, namely converting the gamma ray into light and converting the light to electric signal. Hence, the semiconductor detector has a higher conversion efficiency to an electric signal than the scintillation detector. Furthermore, since a semiconductor cell can independently detect gamma rays, energy resolution and counting efficiency are higher than in the scintillation detector. A technology using such a radiation semiconductor detector is disclosed in Japan Laid-Open Patent Application No. 11-281747, for example.

Meanwhile, the conventional PET imaging system usually has an image reconstruction apparatus, an image display apparatus, or the like in addition to an instrumentation apparatus including the PET apparatus. Furthermore, an image reconstruction algorithm (image reconstruction information) for reconstructing an image in the image reconstruction apparatus is fixed when the apparatus is shipped. Because of this, there may be problems in that the image reconstruction apparatus itself should be changed in a case where the image reconstruction algorithm is changed and that the image reconstruction apparatus cannot be used with the change of the image reconstruction algorithm.

Furthermore, since hardware resources in the above-discussed PET imaging system are extremely expensive, a imaging system wherein separate apparatuses such as a scanner part for scanning the object to be examined, a host computer for reconstructing a medical image from information of the object to be examined that is scanned by controlling the scanner part, a user terminal indicating the reconstructed image, or the like, are connected by a network such as the Internet may be used. In this case, however, since control data in the scanner part are managed in a unified manner at the side of the host computer, it is difficult to change a scan parameter or the like with a user terminal. Furthermore, when the number of the user terminals increases, the load on the host computer increases.

SUMMARY OF THE INVENTION

Accordingly, it is a general object of the present invention to provide a novel and useful positron emission tomography imaging system, detector, data processing apparatus, computer readable program product having a positron emission tomography imaging program for a user terminal, and method for positron emission tomography diagnosis, in which one or more of the problems described above are eliminated.

Another and more specific object of the present invention is to provide a positron emission tomography imaging system, detector, data processing apparatus, computer readable program product having a positron emission tomography imaging program for a user terminal, and method for positron emission tomography diagnosis, whereby cost for equipment at a user side can be reduced by distributing the user terminal and a scanner (detector), tolerance against an obstruction can be improved by load-sharing, and it is possible to reconstruct the medical image by using the data processing apparatus and easily add, change, or the like the image reconstruction algorithm.

The above object of the present invention is achieved by a positron emission tomography imaging system, including:

-   -   a detector configured to detect radiation emitted from an object         to be examined;     -   a data processing apparatus configured to reconstruct image data         for positron emission tomography diagnosis from detection data         obtained from the detector; and     -   a user terminal configured to obtain desired information by         operating the detector and the data processing apparatus;     -   wherein the detector includes     -   a detection part having a plurality of detection elements         configured to detect the radiation emitted from the object to be         examined for every designated timing; and     -   an event information file generation part configured to generate         an event information file based on the detection data obtained         from the detector; and     -   wherein the data processing apparatus includes     -   a coincidence information generation part configured to generate         coincidence information based on the event information file; and     -   an image reconstruction part configured to reconstruct the image         data based on the coincidence information obtained by the         coincidence information generation part and image reconstruction         information set in advance by the user terminal.

The above object of the present invention is also achieved by a positron emission tomography imaging system, including:

-   -   a detector configured to detect radiation emitted from an object         to be examined;     -   a data processing apparatus configured to reconstruct image data         for positron emission tomography diagnosis from detection data         obtained from the detector; and     -   a user terminal configured to obtain desired information by         operating the detector and the data processing apparatus;     -   wherein the detector includes     -   means for detecting the radiation emitted from the object to be         examined for every designated timing by a plurality of detection         elements; and     -   means for generating an event information file based on the         detection data obtained from the detector; and     -   wherein the data processing apparatus includes     -   means for generating coincidence information based on the event         information file; and     -   means for reconstructing the image data based on the coincidence         information and image reconstruction information set in advance         by the user terminal.

According to the above-mentioned inventions, it is possible to achieve load sharing and improve a tolerance against an obstruction. Furthermore, it is possible to reduce the equipment cost of the detector or the user terminal. In addition, since the algorithm at the time of image reconstruction can be set as image reconstruction information, it is possible to easily change the algorithm, compare the image data at the different algorithms, or the like. Furthermore, by separating the user terminal from the detector, it is possible to provide a free degree to an arrangement of the user terminal.

The event information file generation part may generate the event information file based on the detection data, detector information including position information of the detection elements, and synchronous information for synchronizing a detection time by detection elements.

The means for generating the event information file may generate the event information file based on the detection data, detector information including position information of the detection elements, and synchronous information for synchronizing a detection time by detection elements.

According to the above-mentioned inventions, it is possible to efficiently reconstruct image data at high precision based on the event information file formed by the detection data, the detector information, and the synchronous information, by the data processing apparatus. Furthermore, since only the event information file is required to be transmitted to the data processing apparatus, it is possible to reduce the amount of transmission as compared to a case where the image data are transmitted.

The data processing apparatus may include

-   -   a plurality of the coincidence information generation parts and         the image reconstruction parts, and     -   a management part configured to distribute a process for         generating the coincidence information and a process for         generating the event information file so as to make the         coincidence information generation part and the image         reconstruction part perform the respective processes.

The data processing apparatus may include

-   -   a plurality of the means for generating the coincidence         information and the means for reconstructing the image, and     -   means for distributing a process for generating the coincidence         information and a process for generating the event information         file so as to make the means for generating the coincidence         information and the means for reconstructing the image perform         the respective processes.

According to the above mentioned inventions, it is possible to distribute loads at the data processing apparatus. In addition, it is possible to improve process efficiency, by making plural processes be simultaneously done in parallel by the managing part or the means for distributing. Furthermore, it is possible to reduce the equipment cost of hardware at the detector or the user terminal, or the processing load.

The above object of the present invention is also achieved by a detector configured to detect radiation emitting from an object to be examined, including:

-   -   a detection part having detection blocks where a plurality of         detection elements are provided facing the object to be         examined, the detection part configured to generate detection         data from identification information of the detection elements         detecting the radiation at every designated timing and detection         time information, and     -   an event information file generation part configured to generate         an event information file based on the detection data obtained         by the detection part, detector information including position         information of the detection elements, and synchronous         information for synchronizing a detection time by the detection         elements.

The above object of the present invention is also achieved by a detector for detecting radiation emitting from an object to be examined, including:

-   -   means for generating detection data from identification         information of detection elements detecting the radiation at         every designated timing and detection time information; and     -   means for generating an event information file based on the         detection data obtained by means for detecting, detector         information including position information of the detection         elements, and synchronous information for synchronizing a         detection time by the detection elements.

According to the above-mentioned inventions, it is possible to efficiently reconstruct image data at high precision based on the event information file formed by the detection data, the detector information, and the synchronous information, by the data processing apparatus. Furthermore, since the only event information file is required to be transmitted to the data processing apparatus, it is possible to reduce the amount of transmission as compared to a case where the image data are transmitted.

The detection part may detect the radiation emitting from the object to be examined by moving the detector blocks or the detection elements, and

-   -   the detector information may include position information for         every one of the detection elements.

The means for detecting may include detection blocks having the detection elements,

-   -   the means for detecting may detects the radiation emitting from         the object to be examined by moving the detector blocks or the         detection elements, and     -   the detector information may include position information for         every one of the detection elements.

According to the above-mentioned inventions, the radiation is detected by moving the detector blocks or the detection elements. The event information file can be generated with high precision by using information of a moving position of the detector blocks or the detection elements.

The above object of the present invention is achieved by a data processing apparatus configured to reconstruct image data for positron emission tomography diagnosis from detection data obtained from a detector detecting radiation emitted from an object to be examined, including

-   -   a coincidence information generation part configured to extract         detection elements that simultaneously detect the radiation from         the detection data, detector information, synchronizing         information for synchronizing a detection time at each of the         detection elements, and configured to generate coincidence         information based on identification information, information         about the number, and time information of the extracted         detection elements, and     -   an image reconstruction part configured to reconstruct the image         data based on the coincidence information obtained by the         coincidence information generation part and image reconstruction         information set in advance.

The above object of the present invention is achieved by a data processing apparatus for reconstructing image data for positron emission tomography diagnosis from detection data obtained from a detector detecting radiation emitted from an object to be examined, including

-   -   means for extracting detection elements simultaneously detecting         the radiation from the detection data, detector information, and         synchronizing information for synchronizing a detection time at         the detection elements,     -   means for generating coincidence information based on         identification information, information about the number, and         time information of the extracted detection elements, and     -   means for reconstructing the image data based on coincidence         information obtained by the means for generating coincidence         information and image reconstruction information set in advance.

According to the above-mentioned inventions, it is possible to easily generate the coincidence information from the detection data, detector information, and the synchronizing information so that image data having high precision can be reconstructed. Furthermore, it is possible to achieve load sharing and improve a tolerance against an obstruction and to reduce the equipment cost of the detector or the user terminal, by providing the data processing apparatus. In addition, since the algorithm at the time of image reconstruction can be set as image reconstruction information, it is possible to easily change the algorithm, compare the image data with the different algorithms, or the like.

The above object of the present invention is achieved by a computer readable program product having a positron emission tomography imaging program for a user terminal, the program being implemented by a computer so as to reconstruct image data for positron emission tomography diagnosis by a data processing apparatus based on detection data from a detector detecting a radiation emitted from an object to be examined, the program including the steps of:

-   -   a) detecting the radiation emitted from the object to be         examined for every designated timing by a detection element of         the detector,     -   b) generating an event information file based on the detection         data obtained in the step a),     -   c) generating coincidence information based on the event         information file by the data processing apparatus, and     -   d) reconstructing image data based on the coincidence         information obtained in the step c) and image reconstruction         information set in advance.

The above object of the present invention is also achieved by a method for positron emission tomography diagnosis whereby data from a detector detecting radiation emitted from an object to be examined are extracted, and image data for the positron emission tomography diagnosis are reconstructed so as to be output to a user terminal, the method including the steps of:

-   -   a) detecting the radiation emitted from the object to be         examined for every designated timing by a detection element of         the detector,     -   b) generating an event information file based on the detection         data obtained in the step a),     -   c) generating coincidence information based on the event         information file, and     -   d) reconstructing image data based on the coincidence         information obtained in the step c) and image reconstruction         information set in advance.

According to the above-mentioned inventions, it is possible to achieve load sharing and improve tolerance against an obstruction. Furthermore, it is possible to reduce the equipment cost of the detector or the user terminal. In addition, since the algorithm at the time of image reconstruction can be set as image reconstruction information, it is possible to easily change the algorithm, compare the image data with the different algorithms, or the like. Furthermore, by using the program, it is possible to easily do processing by an all-purpose computer without any special apparatus structure.

In the above-mentioned step b), the event information file may be generated based on the detection data, detector information including position information of the detection elements, and synchronous information for synchronizing a detection time.

According to the above-mentioned invention, it is possible to efficiently reconstruct the image data having high precision from the detection data, detector information, and the synchronizing information, by the data processing apparatus.

Other objects, features, and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an example of a structure of a PET imaging system of the present invention;

FIG. 2 is a schematic view showing an example of a structure of a PET apparatus of the present invention;

FIG. 3 is a view showing an example of data stored in a storage part of the present invention;

FIG. 4 is a schematic view showing an example of structures of hardware for a user terminal whereby a PET imaging process of the present invention can be realized;

FIG. 5 is a table showing an example of data of coincidence information of the present invention;

FIG. 6 is a flowchart showing an example of processes for activating a detector by the user terminal; and

FIG. 7 is a flowchart showing an example of processes for activating a data processing apparatus by the user terminal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will now be given, with reference to FIG. 1 through FIG. 7, of embodiments of a positron emission tomography imaging system, detector, data processing apparatus, computer readable program product having a positron emission tomography imaging program for a user terminal, and method for positron emission tomography diagnosis of the present invention.

[System Structure]

FIG. 1 is a schematic view showing an example of a structure of the PET imaging system of the present invention. Referring to FIG. 1, a PET imaging system 10 includes a plurality of detectors 11-1 through 11-n (n is equal to or more than 2), a plurality of user terminals 12-1 through 12-n, and a data processing apparatus 13, which are respectively connected to each other by a communication network 14 such as the Internet.

The detector 11 includes a PET apparatus 21, a synchronous apparatus 22, a file management part 23, a storage part 24, and a network interface part 25.

The data processing apparatus 13 includes a dispatcher 31, a plurality of coincidence detection apparatuses 32-1 through 32-n, and a plurality of image reconstruction apparatuses 33-1 through 33-n.

A radioactive compound is introduced into the object to be examined in advance in order to that the detector 11 obtains detection data from the object to be examined. The detector 11 spatially and timely detects radiation emitting from the object to be examined. More specifically, in this embodiment, the PET apparatus 21 is used as detection means and therefore annihilation gamma rays emitted from the object to be examined are detected. The detector 11 generates an event information file formed by a detection time, an identification number of the detector, and structural information of the detector.

In the PET apparatus 21 of the detector 11, the annihilation gamma rays emitting at the time when the positron emitted from the radioactive compound introduced in the body of the object to be examined and a vicinage electron are combined and extinguished, are detected by a plurality of detection elements provided surrounding the object to be examined. The timing for detection is controlled by the synchronous apparatus 22.

The PET apparatus 21 outputs obtained detection data and detector information to the file management apparatus 23. Furthermore, the synchronous apparatus 22 outputs synchronous information for synchronizing detection time of radiation in the plurality of detection elements, to the file management part 23.

Although the PET apparatus 21 is shown in FIG. 1 as a detector or means for detecting, the present invention is not limited to this. For example, a single photon emission computed tomography (SPECT) apparatus can be used as the detector or means for detecting. Detailed structure of the PET apparatus 21 is discussed below.

The file management part 23 generates the event information file based on data obtained from the PET apparatus 21 and the synchronous apparatus 22 and functions as an event information file generation part (means for generating an event information file). The file management part 23 outputs the generated event information file to a network interface part 25. Furthermore, the file management part 23 stores the generated event information file at the storage part 24 and sends the event information file from the network interface part 25 corresponding to a request from the user terminal 12 or the data processing apparatus 13. The network information interface part 25 sends data to or receives data from the user terminal 12 or the data processing apparatus 13 via the communication network 14.

Furthermore, the file management part 23 performs an authorization process against an access from the user terminal 12, if necessary. In this case, authorization information such as user identification (ID) or pass word is stored in the storage part 24 in advance. The file management part 23 obtains the user ID or the pass word from the storage part 24 at the time of the authorization process so that the authorization process is performed.

The user terminal 12 sends an instruction to the detector 11 and the data processing apparatus 13 to make them execute an event and a process (detection of the coincidence and image reconstruction) so that the reconstructed image data are obtained and indicated for diagnosis. The user terminal 12 can be connected to the communication network 14. Hence, at a work station, or the like, the instruction can be sent to the detector 11 and the data processing apparatus 13 and the image information necessary for diagnosis or the like can be obtained from the detector 11 or the data processing apparatus 13, by installing a PET imaging program to an all-purpose personal computer. Thus, the PET diagnosis process of the present invention can be realized through the user terminal 12. Detailed structure of the user terminal 12 is discussed below.

The data processing apparatus 13 inputs the event information file based on the instruction from the user terminal 12 and reconstructs the image data by detection of the coincidence and image reconstruction algorithm. The dispatcher 31 works as a management part (means for managing) so as to distribute processes to plural coincidence detection apparatuses 32 and image reconstruction apparatuses 33 in order to reduce the load on the data processing apparatus 13. Furthermore, in a case where some of the coincidence detection apparatuses 32 and image reconstruction apparatuses 33 go wrong, the dispatcher 31 makes other coincidence detection apparatuses 32 and image reconstruction apparatuses 33 process so that interruption of the process can be prevented.

Plural image reconstruction algorithms are stored in the dispatcher 31 in advance. The dispatcher 31 makes the respective image reconstruction apparatuses 33-1 through 33-n perform the image reconstruction process based on the image reconstruction algorithm selected by the user terminal 12.

Furthermore, the dispatcher 31 performs an authorization process against an access from the user terminal 12, if necessary. In this case, authorization information such as user identification (ID) or password is stored in the dispatcher 31 in advance.

The coincidence detection apparatus 32 functions as a coincidence information generation part (means for generating coincidence information). That is, the coincidence detection apparatus 32 generates coincidence information based on the event information file from the detector 11 through the instruction from the user terminal 12. More specifically, the coincidence detection apparatus 32 generates the coincidence information by simultaneously extracting information about the number, a position, or the like of the detection elements detecting the annihilation gamma rays so as to output the coincidence information to the image reconstruction apparatus 33 performing the image reconstruction process set by the dispatcher 31. The image reconstruction apparatus 33 functions as an image reconstruction part (means for reconstructing image).

The image reconstruction apparatus 33 follows the image reconstruction algorithm set by the dispatcher 31 and reconstructs the image data based on the coincidence information from the coincidence detection apparatus 32. The reconstructed image data are output to the dispatcher 31. The dispatcher 31 outputs the image data to a designated user terminal. Details of the data processing apparatus 13 are discussed below.

As described above, according to the PET imaging system 10 of the present invention, cost for equipment at a user side can be reduced by distributing the user terminal and a scanner (detector), and tolerance against an obstruction can be improved by load-sharing. In addition, since the algorithm at the time of image reconstruction can be set as image reconstruction information, it is possible to easily change the algorithm, compare the image data with the different algorithms, or the like.

Furthermore, it is possible to correspond to the change of the algorithm for image reconstruction or the like, within the data processing apparatus 13 without making a big change for every detector. Hence, it is possible to reduce operations cost.

[PET Apparatus]

Next, an example of the PET apparatus of the present invention is discussed. FIG. 2 is a schematic view showing an example of a structure of the PET apparatus of the present invention.

Referring to FIG. 2, the PET apparatus 21 includes detector blocks 41-1 through 41-4, preamps 42-1 through 42-4, information processing means 43, control means 44, image reconstruction means 45, and output means 46. The detector blocks 41-1 through 41-4 are formed by arrangement of plural detection elements. The preamps 42-1 through 42-4 amplify detected signals. The information processing means 43 obtains the signal from the preamp 42 so as to perform information processing. The control means 44 controls the information processing means 43. The image reconstruction means 45 displays image data processed by the information processing means 43. The output means 46 outputs the detection data and information about the detector to the file management part 23.

One step of two steps of the detector blocks 41 shown in FIG. 2 is stuck. A semiconductor solid element is used for the detector. Because of this, miniaturization and low cost of the device are realized. There are “n”×“m” semiconductor solid elements are arranged and a surface of an element at a side of the object to be examined is set 1 mm×1 mm, for example. Because of this, it is possible to obtain detailed three-dimensional distribution information of a positron emission radioactive isotope in the object 47 to be examined at a spatial resolution equal to or less than 1 mm.

As shown in FIG. 2, the detector blocks 41 are arranged so as to face the object 47 to be examined and form a pair of detector block. In the PET apparatus 21, the positron and electron are combined so that two annihilation gamma rays are emitted in a direction opposite to the object to be examined. As shown in FIG. 2, the annihilation gamma rays are detected by the detector blocks 41 facing each other.

In this embodiment, respective detector blocks 41-1 through 41-4 may be moved every block during the instrumentation and plural elements forming the respective detector blocks may be moved every element. Information about a position where the element moves is stored as detector information.

An electric signal from respective detector blocks 41 is amplified by an operational amplifier 42 and output to the information processing means 43. The information processing means 43 determines whether the annihilation gamma rays are detected simultaneously by plural detection elements. Only if the annihilation gamma rays are detected simultaneously by plural detection elements, are the data used as detection data.

The information processing means 43 outputs the obtained signal, an instrumentation state or result, or the like to the image reconstruction means 45. The information processing means 43 may generate the reconstructed image by a fixed image reconstruction algorithm set in advance and output it to the image reconstruction means 45.

The control means 44 outputs the detection data obtained by the information processing means 43 and the detector information about a structure, performance, or the like about the detector to the output means 46 in real time, at an every designated timing, or when scanning is completed. The output means 46 outputs the detection data and the information about the detector to the file management part 23.

Next, details of data stored in the detector 11 are discussed below. Information about the object to be imaged (name of the object to be examined, date of image taking, or the like), information about a condition of image taking (pixel size, information about the structure, information about an apparatus of image taking, or the like), and type of information (event information, synchronizing information, or the like) are stored as data in the detector 11. An example of the stored data is discussed with reference to FIG. 3.

FIG. 3 is a view showing an example of data stored in a storage part of the present invention. More specifically, an example of the detection data is shown in FIG. 3-(a), a data example of the detector information is shown in FIG. 3-(b), and an example of the synchronizing information is shown in FIG. 3-(c).

The detection data shown in FIG. 3-(a) are formed by time information, channel number, or the like. More specifically, a channel number (element identification information) for identifying the element detecting the annihilation gamma rays and its time information (a value of a counter) are stored.

The time information is a value of a counter inside of the detection part (approximately 48 bits, the unit is approximately 4 ns) and controlled by the synchronous apparatus 22. In FIG. 3-(a), a channel number of a channel at which the event occurs is stored as position information of the detected element. In an example shown in FIG. 3-(a), events simultaneously occur at a channel 250 and channel 730 at the time of 1000 ns. Hence, the annihilation gamma rays are simultaneously detected at these two channels.

The detector information shown in FIG. 3-(b) is formed by proofreading time, proofreading information of a detection element 1, proofreading information of a detection element 2, or the like. More specifically, the position information about the detector is stored.

The proofreading information of a single detection element is formed by coordinates (X, Y, Z) of the detection element from the view of a certain coordinate origin and a data sequence such as parameter 1, parameter 2, or the like. Since the respective detector blocks 41-1 through 41-4 shown in FIG. 2 are moved every block during the instrumentation and plural elements forming the respective detector blocks 41 may be moved every element, information about the position where the element moves is stored as shown in FIG. 3-(b). The parameter such as the parameter 1 or the parameter 2 shows an action parameter of each of the detection elements such as a bias voltage of the detection element or a threshold value of the annihilation gamma rays for deeming the detection.

In the detector 11, since the detector block may move or the object to be examined may move, for example, information of the detector or the object to be examined may be stored at every time step.

FIG. 3-(c) shows synchronizing information from the synchronous apparatus 22, more specifically values at plural channels such as CH1, CH2, or the like, of the synchronous apparatus 22. Respective channels of the synchronous apparatus 22 are sampled at a periodic interval such as 10 ms. An analog-to-digital (A/D) converter having approximately 8 channels, for example, is periodically operated and obtained values are recorded as values of the synchronous apparatus 22. The time information, values read out at respective channels of the A/D converter at respective times, are stored. Because of this, it is possible to convert the movement of a portion, which is an object of instrumentation such as lungs of the object to be examined, for example, to a signal.

Corresponding to a request from the user terminal 12, the event information file formed by the data shown in FIG. 3 is output from the network interface part 25 to the user terminal 12 or the data processing apparatus 13. Because of this, it is possible to efficiently reconstruct the image data with the data processing apparatus 13.

[User Terminal]

Next, details of the structure of the user terminal 12 are discussed. As described above, the PET diagnosis process of the present invention can be realized by installing the PET imaging program in the all-purpose personal computer.

[Hardware Structure]

First, an example of a hardware structure of a computer implemented for the present invention is discussed with reference to FIG. 4. FIG. 4 is the schematic view of the structure of the hardware for the user terminal 12 whereby the PET imaging process of the present invention can be realized.

A computer main body shown in FIG. 4 includes an input device 51, an output device 52, a drive device 53, a auxiliary storage device 54, a memory device 55, a central processing unit (CPU) 56 for implementing various controls, and a network connection device 57. They are connected to each other by a system bus B. A “computer readable program product having positron emission tomography imaging program” in claims includes not only a recording medium 58 discussed below but also the auxiliary storage device 54 and the memory device 55.

The input device 51 includes a key board and a pointing device such as a mouse used by the user. Various operating signals such as the execution of a program are input by the operator. The output device 52 includes a display to indicate data or windows necessary for operating the computer main body for the PET imaging process of the present invention. By a control program of the CPU 56, it is possible to indicate the progress of the execution of the program, a result, or the like on the display.

The executive program installed in the computer main body is provided, for example, by the recording medium 58 such as a CD-ROM, or the like. The recording medium 58 where the program is recorded can be set to the drive device 53. The executive program included in the recorded medium 58 is read out from the recording medium 58 so as to be installed in the auxiliary storage device 54.

The auxiliary storage device 54 such as a hard disk functions as a storage means. By the auxiliary storage device 54, it is possible to store the executive program, the event information, the control program provided in the computer, or the like, and input/output them if necessary.

Based on the control program such as an operating system (OS) or the executive program read out and stored in the memory device 55, the CPU 56 controls all the processes of the computer such as various operations or input/output of the data to/from the hardware structure part, so that respective processes in the PET diagnosis can be realized. The various information items necessary for execution of the program can be obtained from the auxiliary storage device 54 and stored.

By connecting to a communication network or the like, the network connection device 57 can obtain the executive program from another terminal connected to the communication network or the like and provide a result of the execution of the program or the executive program itself to another terminal or the like.

According to the above-discussed structure, it is possible to realize the PET imaging process without a specific device structure by installing the program in an all-purpose personal computer or work station, for example.

[Data Processing Apparatus 13]

Next, details of the data processing apparatus 13 are discussed. Based on the instruction from the user terminal 12, the event information file is input by the data processing apparatus 13 so that coincidence is detected and image data by the image reconstruction algorithm are reconstructed. As described above, the dispatcher 31 works as a management part so as to distribute processes to plural coincidence detection apparatuses 32 and image reconstruction apparatuses 33 in order to reduce the load on the data processing apparatus 13.

The dispatcher 31 uses a management method wherein common object request broker architecture (CORBA) is used as a distribution object so as to perform the process without stopping even if some calculating machine stops working. Hence, in a case where either coincidence detection apparatus 32 or image reconstruction apparatus 33 goes wrong, it is possible to prevent interruption of the process by using other coincidence detection apparatuses 32 and image reconstruction apparatuses 33.

Furthermore, plural image reconstruction algorithms are stored in the dispatcher 31 in advance, Hence, it is possible to implement the image reconstruction process at respective image reconstruction devices 33-1 through 33-n by the image reconstruction algorithms selected by the user terminal. Because of this, for example, in a case where the algorithm for the image reconstruction or the like is developed at the user side, the algorithm can be easily used from another user terminal connected to the communication network by registering it with the dispatcher 31 after the development.

Receiving the instruction from the user terminal 12, the coincidence detection apparatus 32 generates the coincidence information based on the event information file from the detector 11. More specifically, the coincidence detection apparatus 32 extracts information of the number and positions of the detection elements which simultaneously detect the annihilation gamma rays from the event information file so as to generate the coincidence information. The coincidence detection apparatus 32 also outputs the coincidence information to the image reconstruction apparatus 33 which actually performs the image reconstruction process and which is set by the dispatcher 31.

Next, an example of data of the coincidence information is discussed with reference to FIG. 5. FIG. 5 is a view showing the example of data of coincidence information of the present invention. The example of the data shown in FIG. 5 corresponds to the detection data shown in FIG. 3-(a). The example of the data shown in FIG. 5 is formed by time information, the number of detection elements which simultaneously detect, and the detection element number that is identification information for identifying the detection elements which actually detect. Although the same value as the channel number shown in FIG. 3-(a) is stored as the detection element number in FIG. 5, another identification number may be stored. The detection element number and the position information number are correlated by the detector information shown in FIG. 3-(b) or the like included in the event information file. Thus, the image data can be reconstructed based on the coincidence information.

Furthermore, the image reconstruction apparatus 33 follows the image reconstruction algorithm set by the dispatcher 31 and reconstructs the image data based on the coincidence information from the coincidence detection apparatus 32. As the reconstruction algorithm for reconstructing the image data of the present invention, for example, a simple back projection method, a Fourier transmission method, an iterative approximation method, a filtered back projection method, or the like may be used. By the simple back projection method, projection data obtained by a beam passing through a certain point (x, y) is back-projected on an original path. Then, this is simply added in any directions so that reconstructed image data are reconstructed. By the Fourier transmission method, a distribution f(x, y) of an absorption coefficient is obtained from an aggregation of projection data P. Thus, it is possible to selectively perform the image reconstruction by using the algorithm set in advance among various reconstruction algorithms. Because of this, it is possible to evaluate the precision of the algorithm by reconstructing the image data from the same event information file by plural image reconstruction algorithms and comparing the contents of the reconstructed image data, for example, so that the PET imaging system having a high added value can be provided.

It is not necessary to provide the dispatcher 31, the coincidence detection apparatus 32, and the image reconstruction apparatus 33 at the same place. The dispatcher 31, the coincidence detection apparatus 32, and the image reconstruction apparatus 33 may be provided at different places on the communication network or the like.

Next, detailed process steps of the above-discussed PET imaging process are discussed with reference to a flowchart of FIG. 6.

[Operation Process Steps to Detector]

FIG. 6 is a flowchart showing an example of processes for activating the detector by the user terminal 12.

In the detection process steps shown in FIG. 6, the user terminal 12 selects a detector which should be activated among plural detectors 11-1 through 11-n (S01). Next, the identification process is done against the selected detector 11 (S02). In the identification process, which detector can be used is set in advance for every user terminal and it is possible to prevent illegal use from other terminals by using the identification process. The identification at the detector 11 is done by the data management part 23 via the above-mentioned network interface part 25. The identification process is done by a user ID and a password, for example. The user information for the identification and the password are managed at the storage part 24 in advance.

Next, whether the identification is OK is determined (S03). If the identification is OK, namely YES in S03, a parameter for activating the detector is set (S04). The parameter is, for example, how the PET apparatus 21 is activated, at which timing output is performed, the contents of activation of the detection elements, information about the object to be examined, position information for scanning, or the like. After the parameter is completed being set, a scanning process for the object to be examined is implemented (S05).

Then, whether the process set in S04 is completed is determined (S06). If the process set in S04 is completed, namely YES in S06, the detection data, data of the detector information, or the synchronizing information is output by the file management part 23 (S07), so that the event information file is generated at the file management part 23 (S08). If the process set in S04 is not completed, namely NO in S06, the scanning process of S05 is continuously done until the process set in S04 is completed.

If the identification is not OK, namely NO in S03, the process is ended in that state. A message about an identification error may be sent to the user terminal or the process may go back to the selection of the detector of S01.

[Operation Process Steps to Data Processing Apparatus]

Next, steps for activating the data processing apparatus 13 by the user terminal 12 are discussed. FIG. 7 is a flowchart showing an example of processes for activating the data processing apparatus 13 by the user terminal 12.

In the detection process steps shown in FIG. 7, the user terminal 12 is identified against the data processing apparatus 13 (S11) so as to identify the user terminal for prevention of the illegal use of the data processing apparatus 13. In the data processing apparatus 13, the identification process is done by the dispatcher 31. For example, the identification is done by the user ID or the password.

Next, the data processing apparatus 13 determines whether the identification is OK (S12). If the identification is OK, namely YES in S12, the user terminal 12 sets the process contents (S13). More specifically, setting about which event information file is used from which detectors for image reconstruction or the selection of the image reconstruction algorithm is done.

Next, the data processing apparatus 13 obtains the event information file set by the user terminal 12 (S14). The event information file is obtained by direct access from the data processing apparatus 13 to the detector 11 set by the user terminal 12 or obtained by transmission from the user terminal 12.

Next, the dispatcher 31 selects a coincidence detection apparatus and the image reconstruction apparatus used for the process from the plural coincidence detection apparatuses 32-1 through 32-n and image reconstruction apparatus 33-1 through 33-n which are managed by the dispatcher 31 (S15). The dispatcher 31 outputs the event information file to the selected coincidence detection apparatus 32 (S16).

The selected coincidence detection apparatus 32 detects (extracts) the coincidence by the input event information file (S18) so as to output the generated coincidence information to the image reconstruction apparatus 33 selected by the dispatcher 31 (S18). At this time, the dispatcher 31 sets the image reconstruction algorithm set in advance by the user terminal 12 to the image reconstruction process at the selected image reconstruction apparatus 33.

The image reconstruction apparatus 33 reconstructs the image data based on the set reconstruction algorithms (S19). The reconstructed image data are output to the user terminal set by the dispatcher 31.

If the identification is not OK, namely NO in S12, the process is ended in that state. A message about an identification error may be output to the user terminal or the process may go back to the identification step of S11 so that the user ID and the password may be re-input.

Thus, based on the PET imaging program of the present invention, the user terminal 12 can display the reconstructed image data for the PET diagnosis on the display of the user terminal 12 by activating the detector 11 and the data processing apparatus 13. The process for setting or the like in the above-discussed process steps may be displayed as a setting picture, executive picture, or the like on the display of the user terminal by the executive program and may be set by use of the input device such as the key board or the mouse.

As described above, according to the present invention, it is possible to achieve load sharing and improve a tolerance against an obstruction. Furthermore, it is possible to reduce the equipment cost of the detector or the user terminal. In addition, since the algorithm at the time of image reconstruction can be set as image reconstruction information, it is possible to easily change the algorithm, and compare the image data at the different algorithms, or the like. Furthermore, by separating the user terminal from the detector, it is possible to provide a degree of freedom to an arrangement of the user terminal.

Furthermore, according to the present invention, it is possible to perform processes by making respective functions independent of structural parts and doing the processes together. Hence, it is possible to improve capacities and change or exchange ways of each of the functional parts. Because of this, it is possible to easily and flexibly raise the whole system to high functionalities.

The present invention is not limited to these embodiments, but variations and modifications may be made without departing from the scope of the present invention. For example, although the plural detectors 11 and user terminals 12 are provided in the above-discussed embodiment, one and more detectors 11 and user terminals 12 may be used in the present invention. Furthermore, plural data processing apparatuses 13 may be used in the present invention.

This patent application is based on Japanese Priority Patent Application No. 2004-066174 filed on Mar. 9, 2004, the entire contents of which are hereby incorporated by reference. 

What is claimed is:
 1. A positron emission tomography imaging system, comprising: a detector configured to detect radiation emitted from an object to be examined; a data processing apparatus configured to reconstruct image data for positron emission tomography diagnosis from detection data obtained from the detector; and a user terminal configured to obtain desired information by operating the detector and the data processing apparatus, wherein the detector includes a detection part having a plurality of detection elements configured to detect the radiation emitted from the object to be examined for every designated timing, and an event information file generation part configured to generate an event information file based on the detection data obtained from the detector, and wherein the data processing apparatus includes a coincidence information generation part configured to generate coincidence information based on the event information file, and an image reconstruction part configured to reconstruct the image data based on the coincidence information obtained by the coincidence information generation part and an image reconstruction algorithm selected at the user terminal from a plurality of image reconstruction algorithms stored in advance.
 2. The positron emission tomography imaging system as claimed in claim 1, wherein the event information file generation part generates the event information file based on the detection data, detector information including position information of the detection elements, and synchronous information for synchronizing a detection time by detection elements.
 3. The positron emission tomography imaging system as claimed in claim 1, wherein the data processing apparatus includes: a plurality of the coincidence information generation parts and the image reconstruction parts; and a management part configured to distribute a process for generating the coincidence information and a process for generating the event information file so as to make the coincidence information generation part and the image reconstruction part perform the respective processes.
 4. A positron emission tomography imaging system, comprising: a detector configured to detect radiation emitted from an object to be examined; a data processing apparatus configured to reconstruct image data for positron emission tomography diagnosis from detection data obtained from the detector; and a user terminal configured to obtain desired information by operating the detector and the data processing apparatus, wherein the detector includes means for detecting the radiation emitted from the object to be examined for every designated timing by a plurality of detection elements, and means for generating an event information file based on the detection data obtained from the detector, and wherein the data processing apparatus includes means for generating coincidence information based on the event information file, and means for reconstructing the image data based on the coincidence information and an image reconstruction algorithm selected at the user terminal from a plurality of image reconstruction algorithms stored in advance.
 5. The positron emission tomography imaging system as claimed in claim 4, wherein the means for generating the event information file generates the event information file based on the detection data, detector information including position information of the detection elements, and synchronous information for synchronizing a detection time by detection elements.
 6. The positron emission tomography imaging system as claimed in claim 4, wherein the data processing apparatus includes: a plurality of the means for generating the coincidence information and the means for reconstructing the image; and means for distributing a process for generating the coincidence information and a process for generating the event information file so as to make the means for generating the coincidence information and the means for reconstructing the image perform the respective processes.
 7. A data processing apparatus configured to generate image data for positron emission tomography diagnosis from detection data obtained from a detector detecting radiation emitted from an object to be examined, comprising: a coincidence information generation part configured to extract detection elements that simultaneously detect the radiation from the detection data, detector information, synchronizing information for synchronizing a detection time at each of the detection elements, and configured to generate coincidence information based on identification information, information about a number, and time information of the extracted detection elements; and an image reconstruction part configured to reconstruct the image data based on the coincidence information obtained by the coincidence information generation part and an image reconstruction algorithm selected at a user terminal from a plurality of image reconstruction algorithms stored in advance.
 8. The data processing apparatus as claimed in claim 7, wherein the numbers of the coincidence information generation part and the image reconstruction part are plural, and the data processing apparatus further includes a management part configured to distribute a process for generating the coincidence information and a process for generating the event information file so as to make the coincidence information generation part and the image reconstruction part perform the respective processes.
 9. A data processing apparatus for reconstructing image data for positron emission tomography diagnosis from detection data obtained from a detector detecting radiation emitted from an object to be examined, comprising: means for extracting detection elements simultaneously detecting the radiation from the detection data, detector information, and synchronizing information for synchronizing a detection time at the detection elements; means for generating coincidence information based on identification information, information about a number, and time information of the extracted detection elements; and means for reconstructing the image data based on coincidence information obtained by the means for generating coincidence information and an image reconstruction algorithm selected at a user terminal from a plurality of image reconstruction algorithms stored in advance.
 10. The data processing apparatus as claimed in claim 9, wherein the numbers of means for generating the coincidence information and the means for reconstructing image data are plural, and the data processing apparatus further includes means for distributing a process for generating the coincidence information and a process for generating an event information file so as to make the means for generating the coincidence information and the means for reconstructing image data perform the respective processes.
 11. A non-transitory tangible computer readable medium having encoded thereon a positron emission tomography imaging program for a user terminal, the program being implemented by a computer so as to reconstruct image data for positron emission tomography diagnosis by a data processing apparatus based on detection data from a detector detecting a radiation emitted from an object to be examined, the program comprising the steps of: detecting the radiation emitted from the object to be examined for every designated timing by a detection element of the detector; generating an event information file based on the detection data obtained in the detecting the radiation step; generating coincidence information based on the event information file by the data processing apparatus; and reconstructing image data based on the coincidence information obtained in the generating coincident step and an image reconstruction algorithm selected at an user terminal from a plurality of image reconstruction algorithms stored in advance, wherein by the steps above positron emission tomography imaging is provided for medical diagnostic purposes, and wherein, by a separation of the steps of generating coincidence information and reconstructing image data from the steps of detecting the radiation and generating an event information file, load sharing is achieved.
 12. The non-transitory tangible computer readable medium having encoded thereon the positron emission tomography imaging program as claimed in claim 11, wherein, in the generating an event information file step, the event information file is generated based on the detection data, detector information including position information of the detection elements, and synchronous information for synchronizing a detection time by the detection elements.
 13. A method for positron emission tomography diagnosis whereby data from a detector detecting radiation emitted from an object to be examined are extracted, and image data for the positron emission tomography diagnosis are reconstructed by a data processing unit so as to be output to a user terminal, the method comprising the steps of: detecting the radiation emitted from the object to be examined for every designated timing by a detection element of the detector; generating an event information file based on the detection data obtained in the detecting radiation step; generating coincidence information in the data processing unit based on the event information file; and reconstructing image data based on the coincidence information obtained in the generating coincidence information step and an image reconstruction algorithm selected at the user terminal from a plurality of image reconstruction algorithms stored in advance, wherein by the steps above positron emission tomography imaging is provided to a user terminal for viewing, printing, or storing for medical diagnostic purposes.
 14. The method for positron emission tomography diagnosis as claimed in claim 13, wherein, in the generating an event information file step, the event information file is generated based on the detection data, detector information including position information of the detection elements, and synchronous information for synchronizing a detection time. 